Introduction

Invasive Species Defined

What's Being Done

 National Invasive Species Information Center

Submodule 5: Invasive Animals

Historical Consequences of Invasive Animals

A number of invasive animals have made a significant impact in the U.S. over the last 300 years. In the mid-1800s, the European periwinkle snail (Littorina littorea) was introduced as a food source to the Nova Scotia area of eastern Canada. The snail eventually made its way south to the New England coast, where it feeds on the rhizomes (underground stems for plant reproduction) of marsh grasses and on alga that cover rocks along the coast. As it turns out, the rocky coastline of New England that is commonly depicted in photos and vacation brochures is a result of the devastation to coastal vegetation brought about by this snail.

The house mouse (Mus musculus) first arrived in the North America in the early 16th century, probably on the ships of Spanish explorers. This mammal was native to central Asia but spread to Europe hundreds of years ago. It is now found throughout the world. The house mouse is even able to live in inhospitable environments such the tundra and the desert because of its opportunistic abilities. Diseases including bubonic plague, rickettsial pox, and tularemia have been transmitted to humans by house mice.

In the Great Smoky Mountains National Park, a population of wild, or feral hogs, established by the few that escaped from hunting enclosures in 1920, has devastated local plant communities by its selective feeding on tuberous plants and greatly changing the soil by thinning the naturally heavy litter, and mixing organic and mineral layers together. These hogs are hybrid descendents of wild boars (Sus scrofa) native to Europe, Asia, Northern Africa, Japan, and the Malayan Islands, and domestic pigs.

The sea lamprey (Petromyzon marinus) was able to colonize the upper Great Lakes after the completion of the Welland Canal in 1829. The canal, located between Lake Ontario and Lake Erie, allowed this parasitic fish to bypass Niagara Falls. Subsequently, the lamprey entered and established itself in Lakes Huron, Michigan, and Superior, devastating populations of sporting and food fish.

In 1890, 100 European starlings (Sturnus vulgaris) were released into the wild in Central Park, New York. Since then, the number of starlings has increased exponentially with dispersal from southern Canada to northern Mexico. Starlings are able to adapt to a wide range of habitats requiring only holes in trees and buildings for nesting and fields for feeding. They have caused a decrease in native wrens and other birds that inhabit similar cavities. Human activites and habitats do not seem to curtail starling activites and reproduction. These birds have been a help to farmers because they eat insect pests, but they have also been a bane because they can cause crop damage.